Multiple Distributed Energy Resources Research Articles

Hardware-in-the-Loop Simulation of Distributed Intelligent Energy Management System for Microgrids

Microgrids are autonomous low-voltage power distribution systems that contain multiple distributed energy resources (DERs) and smart loads that can provide power system operation flexibility. To effectively control and coordinate multiple DERs and loads of microgrids, this paper proposes a distributed intelligent management system that employs a multi-agent-based control system so that delicate decision-making functions can be distributed to local intelligent agents. This paper presents the development of a hardware-in-the-loop simulation (HILS) system for distributed intelligent management system for microgrids and its promising application to an emergency demand response program. In the developed HILS system, intelligent agents are developed using microcontrollers and ZigBee wireless communication technology. Power system dynamic models are implemented in real-time simulation environments using the Opal-RT system. This paper presents key features of the data communication and management schemes based on multi-agent concepts. The performance of the developed system is tested for emergency demand response program applications.

Autonomous and adaptive voltage control using multiple distributed energy resources

This paper proposes a plug-and-play control method to coordinate multiple distributed energy resources (DER or DE) to regulate voltages in future distribution systems with a high DE penetration. Theoretical analysis shows that there exists a corresponding formulation of the dynamic control parameters with multiple DEs to give the desired responses. Therefore, the proposed control method has a solid theoretical basis. The method is based on dynamically and adaptively adjusting DE control parameters to ensure that actual voltage responses follow the desired outputs. Also, it is based on local and the other DEs' voltages without the need of the full system data and extensive studies to tune the control parameters. Hence, the method is autonomous and adaptive for variable operational situations, and has the plug-and-play feature with a high tolerance to unavailable or inaccurate system data. Thus, it is suitable for broad utility application. Simulation results from various conditions, such as asynchronous start of multiple DEs, disappearance of the original disturbance in the middle of the control process, and operation in looped distribution systems, confirm the performance, validity, and flexibility of the proposed control method. The possible impact of communication latency on the performance of the proposed method is also discussed.

A Decentralized Robust Control Strategy for Multi-DER Microgrids—Part I: Fundamental Concepts

This paper presents fundamental concepts of a central power-management system (PMS) and a decentralized, robust control strategy for autonomous mode of operation of a microgrid that includes multiple distributed energy resource (DER) units. The DER units are interfaced to the utility grid through voltage-sourced converters (VSCs). The frequency of each DER unit is specified by its independent internal oscillator and all oscillators are synchronized by a common time-reference signal received from a global positioning system. The PMS specifies the voltage set points for the local controllers. A linear, time-invariant, multivariable, robust, decentralized, servomechanism control system is designed to track the set points. Each control agent guarantees fast tracking, zero steady-state error, and robust performance despite uncertainties of the microgrid parameter, topology, and the operating point. The theoretical concept of the proposed control strategy, including the existence conditions, design of the controller, robust stability analysis of the closed-loop system, time-delay tolerance, tolerance to high-frequency effects and its gain-margins, are presented in this Part I paper. Part II reports on the performance of the control strategy based on digital time-domain simulation and hardware-in-the-loop case studies.

Power loss reduction in radial distribution system with multiple distributed energy resources through efficient islanding detection

Abstract To provide electric utility service of desired quality at the lowest possible cost, voltage drop and power loss reduction is crucial for distribution network. Distribution systems with Distributed Energy Resources (DER) have shown an enormous potential for power loss and voltage drop reduction. This paper investigates existing islanding detection techniques for feeder performance and proposes a new islanding detection algorithm (NIDA) for node voltage profile improvement and power loss reduction in the distribution network. The NIDA has been validated with three case studies. It has been investigated for its capabilities to improve the feeder performance in electric distribution system. The proposed algorithm outperforms the conventional approaches, which have many limitations to detect the islanding operation. The non-uniform distribution of electric loads, unity power factor, complexities in the design of control interface and functioning of the system in multi-DER environment are the most common obstacles in implementation of existing islanding detection techniques. NIDA is capable of handling the above mentioned complexities. The simulation results show that NIDA can detect islanding formation during the fault condition. The DER(s) provide uninterruptible power supply to sensitive load in the island, maintaining the nodes voltage and the power loss within the permissible limits.